Press brakes are equipped with movable lower and upper tables, sometimes referred to as jaws. Forming tools are mounted to the tables so that when the tables are brought together, a sheet-like workpiece between the forming tables is bent into an appropriate shape. Press brake tables commonly move in a vertical plane. Behind the plane of the tables of a press brake may be mounted a gage block having a forwardly-facing surface against which the edge of a workpiece is urged in order to properly position the workpiece for bending. Various gage blocks, sometimes called back gages, are shown in U.S. Pat. No. 1,346,185 (Eggers), U.S. Pat. No. 4,055,070 (Wingate, et al.), U.S. Pat. No. 4,583,391 (Stafford), and U.S. Pat. No. 5,526,672 (Cain, et al.).
Often, sheet metal workpiece shapes have edges that are oriented at other than right angles to the direction of the desired bend. One may employ a protractor device mounted to the press brake and that includes a straightedge along which the edge of the workpiece can be guided in a direction other than perpendicular to the press brake tables. Here, the angle of the straightedge with respect to the tables is adjusted until the correct angle is obtained, and the workpiece then is fed along the straightedge until the leading portion of the workpiece encounters a gage block behind the vertical plane within which the tables move.
Gage blocks commonly present flat, forwardly-facing bearing surfaces that are parallel to the plane within which the workpiece tables move. When a leading edge of a workpiece is urged against a gage block bearing surface at an acute or obtuse angle to that surface, the pressure of the workpiece against the surface tends to cause the workpiece to slip along the gage surface, resulting in inaccurate bends. The leading end of the workpiece in any event is generally unsupported except for its single point or line of contact with a gage block surface.
It would be desirable to provide a workpiece mounting system for a press brake that would enable the workpiece to be accurately positioned and supported between the tables of the press brake, without the likelihood that the workpiece will slip or otherwise become misaligned.